Richard Harmon has made packages with the ANSI methods and classes that Squeak doesn't have. The vast majority of these changes are additions to the image, not changes, and so they are pretty safe to load. Maybe if enough people test them out, they will end up in the main distribution image. Just load these three changes one after the other:

The Chronology package on SqueakMap provides ANSI compliance in the DateAndTime and Duration protocols. It was tested with the same ANSI test cases and is theredore interchangeable. IMHO, it has the additional advantage of Smalltalk-80 comptability and supports and extends the existing Month, Week, classes in Squeak - brp
There is a new change set on SqueakMap for Squeak 3.2 released 16 Jul 2002 – AFi